title: Far infrared stimulated emission from the ns and nf Rydberg states of NO.
abstract: We report directional far-infrared emission from the υ = 0 vibrational levels of the 9sσ, 10sσ, 11sσ, 9f, and 10f Rydberg states of NO in the gas phase. The emission around 28 and 19 μm from the 9f state was identified as the downward 9f → 8g and subsequent 8g → 7f cascade transitions, respectively. The emission around 38 and 40 μm from the 10f state was identified as the 10f → 9g and 10f → 9dσπ transition, respectively. Following the excitation of the 9sσ, 10sσ, and 11sσ states, the emission around 40, 60, and 83 μm was assigned as the 9sσ → 8pσ, 10sσ → 9pσ, and 11sσ → 10pσ transitions, respectively. In addition to these emission systems originated from the laser-prepared levels, we found the emission bands from the 8f, 9f, and 10f states which are located energetically above the 9sσ, 10sσ, and 11sσ states, respectively. This observation suggests that the upward 8f ← 9sσ, 9f ← 10sσ, and 10f ← 11sσ optical excitation occurs. Since the energy differences between nf and (n + 1)sσ states correspond to the wavelength longer than 100 μm, the absorption of blackbody radiation is supposed to be essential for these upward transitions.
authors.affiliation: Graduate School of Chemical Sciences and Technology, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Furukawa
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Araki
authors.forename: Hiroya
authors.initials: H
authors.lastname: Umeki
authors.forename: Koichi
authors.initials: K
authors.lastname: Tsukiyama
mesh_terms: D007259:Infrared Rays; D009569:Nitric Oxide / Q000737:chemistry*
chemical_list: D009569:Nitric Oxide